JP2000175425A - Drive device for magnetic disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve rotary control accuracy by reducing assembly man-hours and manufacturing cost, reducing data errors due to leakage magnetic flux, improving the efficiency of a motor, and improving the start torque and torque coefficient in the case of an FDD or the like. SOLUTION: A drive ring magnet with 4n poles is provided at a rotor, and 3m pieces of flat coils 5 are provided in annular form at a stator 3, so that a pattern 4 for FG is surrounded. The interval of the flat coils 5 is set to an electric angle of (3/5)±, and a magnetic sensor 6 is arranged at the maximum interval part 20 generated among the flat coils 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive such as a drive for a replaceable flexible disk, and more particularly to an arrangement of a drive magnet and a coil of a spindle motor used in the drive.

[0002]

2. Description of the Related Art In recent years, floppy disk drives (hereinafter referred to as FDDs) have been required to be smaller and thinner.
In addition, higher performance such as improvement in recording density is also required.
Therefore, there is a demand for a spindle motor used in the FDD to be smaller, thinner, and have higher performance.

FIG. 6 is a perspective view showing a flat-plate spindle motor used in a conventional FDD having a drive thickness of 、 inch, and shows a metal-based printed circuit board (1).
2) and a rotor (1) rotatably attached to the stator (3).

FIG. 4 is a sectional view of a main part of a spindle motor used in a conventional FDD. Further FIG.
FIG. 7 is a plan view showing a state in which a rotor (1) and a bearing are removed from a spindle motor used in the FDD according to the related art shown in FIG.

In a known prior art, in the case of a three-phase drive motor, the number of magnetic poles is 4n, and the number of coils is 3n (n is a natural number of 1 or more), as shown in FIG. FIGS. 11 to 13 show the magnetization diagrams of the driving magnets of n = 2 to 4 and the arrangement diagrams of the coils in the three-phase driving motor according to the related art. (A) is a diagram showing the magnetization of the magnet, and (B) is a diagram showing the coil arrangement. The conventional example of FIG. 5 shows a 16-pole 12-coil.

In the conventional example shown in FIGS. 4 and 5,
The stator (3) is formed by a metal base printed board (12), and a plurality of flat coils (5) and small flat coils (7) are annularly separated by 4 / 3π in electrical angle on the metal base printed board (12). Are arranged adjacent to each other.

The electrical angle is defined as a pair of adjacent magnetic poles (N pole and S pole).
Pole) as 2π.

The flat coil (5) and the small flat coil (7) are narrower on the inner peripheral side than on the outer peripheral side, so that current flows as a driving coil of the rotor (1). Further, the flat coil (5) and the small flat coil (7) have different plane sizes. For every three flat coils (5) having a large plane size, one small flat coil (7) having a small plane size is added. Are arranged.

According to FIG. 5, there are nine flat coils (5) having a large plane size and three small flat coils (7) having a small plane size.
They are arranged evenly over 60 ° without any gaps.

On the outer periphery of the flat coil (5) and the small flat coil (7), a pattern (4) for a frequency generator (hereinafter referred to as FG) is formed, and the small flat coil (7) and the FG pattern are formed. A magnetic sensor (Hall element) (6) for position detection is provided between (4) and (4).

Here, the plane size of the small flat coil (7) is smaller than the plane size of the other flat coils (5) because the rotor (1) is located inside the FG pattern (4). This is because a space for disposing the Hall element (6) for detecting the magnetic pole position is secured on the metal base printed board (12).

One small flat coil (7) is attached to the other two small flat coils (7) at an interval of 120 °. A magnetic recording / reproducing head (hereinafter, referred to as a recording / reproducing head) for recording and reproducing data on a floppy disk.
The magnetic head (8) is arranged to move radially on one small flat coil (7) when accessing the disk.

In FIG. 4, the rotor (1) has a driving ring magnet (2) at positions corresponding to the flat coil (5) and the small flat coil (7) on the stator (3).
The FG magnet (9) is provided at a position corresponding to the FG pattern (4) on the stator (3). Then, an FG signal for rotation control is generated by the FG pattern (4) provided on the stator (3) and the FG magnet (9) provided on the outer periphery of the rotor (1).

The driving ring magnets (2) are
It is magnetized to 6 poles. A shaft (14) is fixed to the center of the rotor (1), and the shaft (14) is rotatably held by a bearing (not shown) provided on the stator (3).

[0015]

According to the above-mentioned structure, it is necessary to manufacture a small flat coil (7) having a small plane size in addition to a large (normal size) flat coil (5). , At least 2
Since it is necessary to manufacture and assemble various types of flat coils, there is a problem that the cost of the stator increases.

Further, since the small flat coil (7) having a small plane size is used, the magnetic flux of the magnetic circuit cannot be utilized sufficiently, and the efficiency of the motor deteriorates, and the torque and the torque constant (hereinafter also referred to as Kt) are reduced. There was a problem of becoming smaller. The torque constant is a proportional constant of the generated torque to the applied current. In addition, since the flat coil (5) and the small flat coil (7) of the normal size constitute the stator, the magnetic field intensity is not strictly uniform over the entire circumference, so that the rotational accuracy of the motor is not increased. Was a factor in lowering.

Further, since the magnetic head (8) for recording and reproducing signals from the magnetic disk is close to the upper side of the small flat coil (7) having a small plane size, the flat coil (7)
In some cases, the magnetic flux from the head interlinks with the magnetic head (8) to detect noise, thereby causing a data error.

Still referring to FIG.
When using a pole (8 pole pairs) drive ring magnet (2),
The coil width of one pole (described later) (10) is ideally 360 ° / 16 = 22.5 °, which is the same as the width of the magnetic pole of the magnet (2).

Here, the coil width means the angle between the center lines of the coil windings on both sides having a predetermined thickness, and is equal to the width of the magnetic flux generated by the coil. In order to penetrate through 2), it is ideal that it coincides with the width of the magnetic pole of the magnet (2).

On the other hand, the stator has 12 flat coils (5) corresponding to the 16-pole drive ring magnets (2).
When (7) is arranged, the coil arrangement width (11) becomes 360 ° / 12 = 30 ° as shown in FIG. 18, resulting in a configuration as shown in FIG. 5. The coil arrangement width (11) means the center pitch of each coil.

As shown in FIG. 5, when arranged in this manner, the adjacent flat coils come into contact with each other, so that the actual coil width is smaller than the ideal value, and the efficiency of the motor is lower than the ideal value. There were challenges. Further FIG.
, It is necessary to provide a drawing pattern (not shown) for the magnetic sensor (6), so that the FG pattern (4) cannot be provided over the entire circumference, and there is a rotation area where the FG signal is interrupted. However, there is a problem that precise rotation control is difficult.

On the other hand, when adjacent flat coils generate magnetic fields having different polarities, it is conventionally known that a part of the magnetic flux cancels out directly and the utilization efficiency of the magnetic flux is poor and the generated torque is reduced. For this reason, a technique has been conventionally known in which adjacent flat coils are configured to generate a magnetic field of the same polarity, and the magnetic flux of the drive coil effectively acts on the drive magnetic pole to improve the torque performance. In particular, in order to reduce the thickness of the rotor and the stator in order to reduce the size of an apparatus such as an FDD, and to obtain the required torque performance, a configuration in which adjacent flat coils generate a magnetic field of the same polarity to improve the torque performance. is necessary.

However, with the above configuration, the intensity of the magnetic field generated by the flat coil becomes larger, so that the ratio of the magnetic flux of the drive coil leaking out of the rotor and affecting the magnetic head increases, and the magnetic flux recorded on the floppy disk is increased. There was a problem that data reading / writing was hindered.

It is known that the larger the outer diameter of the motor, the larger the amount of magnetic flux of the driving magnetic poles and the number of windings of the driving coil, thereby generating a large torque and improving the efficiency of the motor.

For this reason, it is effective to increase the outer diameter of the rotor to near the moving range of the magnetic head. However, in this case, the above-described magnetic flux leaking outside the rotor affects the magnetic head. In particular, when the device is used thinly, the distance in the thrust direction between the magnetic head and the drive coil becomes small, so that this effect becomes remarkable, and it interferes with data read / write. To avoid this problem, if the distance between the magnetic head and the drive coil in the thrust direction is increased, this becomes an obstacle to making the device thinner.

The present invention has been made in view of the above circumstances, and relates to a magnetic disk drive. The size of the flat coil (5) constituting the stator is unified to enable the cost reduction of the apparatus and to improve the efficiency. The efficiency is improved by making the coil width (10) of the flat coil (5) closer to the magnetic pole width of the ring-shaped magnet constituting the rotor, precise rotation control is enabled, and the flat coil (5) is improved. It is an object of the present invention to provide a magnetic disk drive that reduces the influence of a magnetic field generated by a magnetic head on a magnetic head.

[0027]

In order to solve the above-mentioned problems, the invention according to claim 1 is based on a method in which a ring is formed on a substrate (12) forming a stator (3) so as to surround a shaft (14). A 3 m (m is a natural number of 2 or more) flat coils (5) circumferentially arranged at an electrical angle of (5/3) π apart from each other; Magnetic disk drive using a three-phase brushless motor having a drive ring-shaped magnet (2) having 4n (n is a natural number of 3 or more) poles provided on a rotor (1) so as to face a flat coil (5) , The largest gap (2) provided between the 3 m flat coils (5) arranged circumferentially.
A magnetic disk drive, wherein one magnetic sensor (6) is arranged in (0). 2. The magnetic disk drive according to claim 1, wherein the maximum gap (20) coincides with the moving operation position of the magnetic head (8). ”, Claim 3
According to the invention described in the above, "the frequency generator pattern (4) formed in an annular shape so as to surround the shaft (14) on the substrate (12) forming the stator (3) and arranged on the circumference. Magnetic disk using a three-phase Y-connection brushless motor having a plurality of flat coils (5) and a drive ring-shaped magnet (2) provided on a rotor (1) so as to face the flat coils (5) In the driving device, the maximum gap (20) provided between the plurality of circumferentially arranged flat coils (5) is matched with the moving operation position of the magnetic head (8). The invention according to claim 4 is characterized in that the pattern for frequency generator (4) is arranged on the inner periphery of the circumferentially arranged flat coil (5). Claim 1 or Claim 3 Placing the magnetic disk drive device. "Provide.

[0028]

1 to 3, FIGS. 7 to 10, FIGS. 14 to 17, and FIGS. 19 to 20 for an FDD including a spindle motor according to an embodiment of the present invention.
This will be described with reference to FIG. The same components as those in the conventional example are denoted by the same reference numerals, and a description thereof will be partially omitted.

FIG. 17 is an exploded perspective view showing the internal structure of the FDD of this embodiment, and shows the positional relationship between the spindle motor (15) and the magnetic head (8).

In FIG. 17, the magnetic head (8) moves at right angles to the axis (14) of the spindle motor (15) to record signals on a magnetic disk (not shown) or to reproduce signals from the disk.

Next, the structure of the spindle motor used in the FDD of the present embodiment will be described with reference to FIG. FIG. 1 is a plan view showing a state where a rotor (1) and a bearing are removed from a spindle motor used for an FDD according to the present invention.

The rotary drive system of the spindle motor used in the FDD of this embodiment is a drive system of three phases, 16 poles, 9 coils, and one sensor.

In FIG. 1, a stator (3) has an iron-based metal base printed board (12) as a stator yoke, a 48-pulse FG pattern (4) formed on the inner periphery thereof, and a flat coil (4). 9) are arranged adjacent to each other so as to surround the FG pattern (4).

Next, the spindle motor used in the FDD according to the present embodiment will be described with reference to FIG. FIG. 3 is a sectional view of a spindle motor used in the FDD according to the present embodiment.

In FIG. 3, the rotor (1) has a drive ring magnet (2) at a position facing the flat coil (5).
However, FG magnets (9) are arranged at positions facing the FG pattern (4).

Returning to FIG. 1, each flat coil (5) is formed smaller on the inner peripheral side than on the outer peripheral side, and has a coil width of 22.5 °. The adjacent flat coils (5) are arranged close to each other so that the coil arrangement width is 37.5 °. However, a gap (flat coil ( 5) is provided as a sensor placement section (20).

The drive ring magnet (2) provided on the rotor (1) opposite to the flat coil (5) is radially magnetized with 16 poles, and is 360 ° / 16 = 2 each.
It has a configuration having an interval of 2.5 °.

Then, the sensor arrangement part (maximum gap part)
The moving area of the magnetic head (8) is arranged so as to face (20).

The flat coil (5) is a rectangular wire having a rectangular cross section. The configuration of the flat coil (5) will be described below with reference to FIGS. FIG. 7 is a perspective view of the flat coil (5) of the spindle motor used in the FDD of the present embodiment.

As shown in FIG. 7, the flat coil (5)
Has a winding start electrode (21) of a rectangular wire and a winding end electrode (22) on the outer periphery. FIG. 8 is a sectional perspective view of the flat coil (5) shown in FIG.

FIG. 10 is a cross-sectional structural view of a rectangular wire used for the flat coil (5) shown in FIG. 7. The copper wire (16) constituting the rectangular wire has a rectangular cross section, and an insulating layer ( 17) and an adhesive layer (18).

FIG. 9 is a cross-sectional view of a single-sided insulated wire having a configuration different from the rectangular wire shown in FIG. 10, and shows a copper wire (16), an insulating layer (17) only on one side, and an adhesive layer (18) only on one side. Consists of

The flat coil (5) wound with a rectangular wire shown in FIG. 10 can be wound with the same number of turns in a smaller volume than a conventional coated wire having a circular cross section, so that a highly efficient motor can be constructed. effective. Further, the flat coil (5) wound with the single-sided insulated wire shown in FIG. 9 can be wound with the same number of turns in a smaller volume, so that there is an effect that a more efficient motor can be configured.

Referring back to FIG. 1, the FDD of the present embodiment
The description of the spindle motor used for will be continued. In FIG. 1, the adjacent flat coil (5) has an electrical angle of (5 /
3) They are arranged at intervals of π, and the mechanical angle is (360 °)
/16)×(5/3)=37.5°.

A first sensor arrangement portion (maximum gap portion) (20) for disposing the Hall element (6) is provided.
Flat coil (5a) and the ninth flat coil (5
The flat coil (5) is arranged at an interval of (8/3) π (mechanical angle of 60 °) only in the interval with i).

[0046]

The mechanical angle is an angle at which the centers of two coils are geometrically sandwiched as shown in FIG.

As described above, in the case of the conventional three-phase drive motor, the number of magnetic poles is 4n and the number of coils is 3n (n is a natural number).

In the spindle motor used in the FDD of this embodiment, the number of magnetic poles is 4n (n is a natural number of 3 or more,
In the example shown in FIG. 1, 16 poles are used, and the number of coils is 3 m (m is 2
The above is a natural number, similarly, 9 coils).

FIG. 15 shows the relationship between the coil arrangement and the magnetic poles of the driving magnet (16 poles, 9 coils) in the configuration shown in FIG. FIG. 15A shows the arrangement of the magnetic poles, and FIG.
5 (B).

As still another configuration example, FIG.
FIG. 16 shows the arrangement of the coils, that is, 20 poles and 9 coils. Hereinafter, FIG. 14, FIG. 19 and FIG.
The following describes the relationship between the drive current applied to the flat coil (5) and the direction of the magnetic field generated by the flat coil (5) when configured as six pole coils. In the layout diagram of the flat coil (5) shown in FIG. 14, the flat coil (5) is numbered for convenience. The flat coil (5) shown in FIG. 14 is connected by three-phase Y connection,
FIG. 19 shows the connection diagram. FIG. 20 is a timing chart of the drive current applied to the flat coil (5). FIG. 20 shows a typical step waveform as the applied current. As can be seen from FIGS. 14 and 20, by arranging the flat coil (5) as shown in FIG. 14, the adjacent flat coil (5) generates a magnetic field of the same polarity in a state where two arbitrary phases are energized. With such a configuration, the magnetic fields in opposite directions do not cancel each other.

Further, referring to FIG. 1, the FDD of the present embodiment
The pattern (4) for the FG of the spindle motor used for the following will be described.

As shown in FIG. 1, the FG pattern (4)
Is formed on the inner peripheral side of the flat coil (5), so that the FG pattern (4) is not disturbed by the lead wire of the magnetic sensor (6). The motor can be formed without interruption over the entire circumference, and the effect of improving the rotation control accuracy of the motor is achieved.

Since the FG magnetic pole (9) is magnetized to 96 poles in this embodiment, the FG pattern (4) is also constituted by a mechanical angle of 360 ° / 96 = 3.75 °. .

At this time, the FG pattern lead line (23)
The cancellation pattern (19) for canceling the effect of
Based on the pattern lead line for G (23), the electric angle of the driving magnet is (2m + 1) π (where m is 0, 1, 2,..., M = 0 in the embodiment), and the width is 22.5. The arrangement at the mechanical angle of ° cancels out the influence of the driving magnet on the FG signal.

FIG. 2 shows an example in which the configuration shown in FIG. 1 is different from that shown in FIG. 1. The same 16-pole, 9-coil as shown in FIG. 1 is used, but the FG pattern (4) is provided on the outer periphery of the coil (5). The arrangement is arranged.

The FDD according to the present embodiment uses the spindle motor having the above-described structure, and the spindle motor has one maximum gap (20) between the annularly arranged flat coils (5). And the magnetic sensor (8) is arranged here, so that it is not necessary to separately manufacture and arrange a small-diameter small flat coil (7) as in the prior art. As a result, the number of assembling steps and the manufacturing cost can be reduced. Further, since the stator is constituted by the flat coil (5) having the same shape, the generated magnetic field becomes uniform over the entire circumference, and there is an effect that the rotation accuracy is improved.

The moving area of the magnetic head (8) is
Since it is arranged in the largest gap of the flat coil (5), the effect of the leakage magnetic flux generated from the flat coil (5) on the magnetic head (8) is reduced, and the frequency of occurrence of a data error by the FDD is reduced. .

In the configuration shown in FIG. 1, the angle between the flat coils (5a) and (5i) at both ends of the gap between the flat coils (5) in which the moving area of the magnetic head (8) is arranged is 60 °.

Further, as described above, since the adjacent flat coils (5) are arranged at an interval forming an electrical angle (5/3) π, the flat coils (5) are energized in arbitrary two phases. In this state, the flat coils (5) adjacent to each other generate a magnetic field of the same polarity, and a phenomenon in which the torque of the motor decreases due to a decrease in efficiency due to the cancellation of magnetic flux as described in the prior art motor is avoided. Is done.
That is, since the applied current required to generate the same level of torque is smaller than the conventional value, the leakage magnetic flux is reduced, and the magnetic head (8) is placed in the largest gap (20) of the flat coil (5) as described above. In addition to the arrangement, there is an effect that data errors due to the influence of the leakage magnetic flux to the magnetic head (8) can be reduced.

Further, since it is not necessary to use the small flat coil (7), the windings of all the flat coils (5) can be provided on the outer periphery, so that the efficiency of the motor is improved, and the starting torque and torque are improved. There is an effect that the constant is improved.

Further, since the number of magnetic poles is 4n (n is a natural number of 3 or more) and the number of coils is 3 m (m is a natural number of 2 or more), the size of the flat coil (5) can be made sufficiently large. Since the coil width of the stator can be made close to the magnetic pole width of the rotor, the efficiency of the motor is improved, and the starting torque and the torque constant are improved.

In the configuration of the present embodiment described above, even in a configuration in which the magnetic sensor (6) is not provided and the motor is driven by a no sensor, the effects of the present invention described above can be similarly obtained. is there.

[0064]

According to the first aspect of the present invention, in the magnetic disk drive, since the size of the flat coil can be increased, the efficiency of the motor is improved, and the starting torque and the torque constant are improved. Since no coil is used, the number of assembling steps is reduced, and the effect of improving rotational accuracy is obtained.

According to the second aspect of the present invention, in the magnetic disk drive, the efficiency of the motor is improved, the starting torque and the torque constant are improved, and the data error is reduced.

The third aspect of the invention has the effect of reducing data errors in the magnetic disk drive.

According to a fourth aspect of the present invention, in the magnetic disk drive, the efficiency of the motor is improved, the starting torque and the torque constant are improved, the data error is reduced, and the rotation control accuracy of the motor is improved. To play.

[Brief description of the drawings]

FIG. 1 is a top view of a spindle motor used in an FDD according to an embodiment of the present invention.

FIG. 2 is a top view of another configuration example of the spindle motor used in the FDD according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of a spindle motor used in the FDD according to the embodiment of the present invention.

FIG. 4 is a sectional view of a spindle motor for FDD according to the related art.

FIG. 5 is a top view of a spindle motor for FDD according to the related art.

FIG. 6 is a perspective view of a spindle motor for FDD according to the related art.

FIG. 7 is a perspective view of a flat coil used in a spindle motor used in the FDD according to one embodiment of the present invention.

FIG. 8 is a sectional perspective view of a flat coil used in a spindle motor used in the FDD according to the embodiment of the present invention.

FIG. 9 is a cross-sectional perspective view of a single-sided insulated wire constituting a flat coil used in a spindle motor used in an FDD according to an embodiment of the present invention.

FIG. 10 is a cross-sectional perspective view of a flat wire constituting a flat coil used in a spindle motor used in an FDD according to an embodiment of the present invention.

FIG. 11 is a layout view of magnetic poles and coils of a spindle motor for FDD according to the related art.

FIG. 12 is a layout diagram of magnetic poles and coils of a spindle motor for FDD according to the related art.

FIG. 13 is an arrangement diagram of magnetic poles and coils of a spindle motor for FDD according to the related art.

FIG. 14 is a layout diagram of magnetic poles and coils of a spindle motor used in an FDD according to an embodiment of the present invention.

FIG. 15 is a layout diagram of magnetic poles and coils of a spindle motor used in an FDD according to an embodiment of the present invention.

FIG. 16 is a layout diagram of magnetic poles and coils of a spindle motor used in an FDD according to an embodiment of the present invention.

FIG. 17 is an exploded perspective view of the FDD according to the embodiment of the present invention.

FIG. 18 is a table showing the numbers of magnetic poles and coils of a spindle motor for FDD according to the related art.

FIG. 19 is a connection diagram of a flat coil having 12 poles and 6 coils in the spindle motor used in the FDD according to one embodiment of the present invention.

FIG. 20 is a timing chart of a drive current applied to a flat coil having 12 poles and 6 coils in a spindle motor used in an FDD according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotor 2 Ring drive magnet 3 Stator 4 Pattern for FG 5 Flat coil 5a Flat coil 5i Flat coil 6 Hall element (magnetic sensor) 7 Small flat coil 8 Magnetic head 9 Magnet for FG 14 Axis 15 Spindle motor 16 Copper wire 17 Insulation Layer 18 Adhesive layer 19 Negative pattern 20 Sensor arrangement part (maximum gap) 21 Winding start electrode 22 Winding end electrode 23 FG pattern lead wire

Claims (4)

[Claims] 1. A frequency generator pattern annularly formed on a substrate forming a stator so as to surround an axis, and 3 m (m is a circle) arranged circumferentially at an electrical angle of (5/3) π. Magnetics using a three-phase brushless motor having two or more natural numbers of flat coils and a drive ring-shaped magnet having 4n (n is a natural number of 3 or more) poles provided on the rotor so as to face the flat coils. The magnetic disk drive according to claim 1, wherein one magnetic sensor is arranged in a maximum gap provided between the 3m flat coils arranged in the circumference. 2. The magnetic disk drive according to claim 1, wherein the maximum gap is made coincident with the moving operation position of the magnetic head. 3. A frequency generator pattern annularly formed on a substrate forming a stator so as to surround an axis, a plurality of flat coils arranged on a circumference, and opposed to the flat coil. In a magnetic disk drive using a three-phase Y-connection brushless motor having a drive ring-shaped magnet provided on a rotor, a maximum gap provided between the plurality of circumferentially arranged flat coils is magnetically provided. A magnetic disk drive device, wherein the magnetic disk drive device matches a moving operation position of a head. 4. The magnetic disk drive according to claim 1, wherein the frequency generator pattern is disposed on an inner peripheral portion of the circumferentially arranged flat coil.